AT&T said Thursday it had restored its U-verse broadband service to all customers who suffered from a widespread outage this week.

The fiber-based TV, Internet and phone service had been out for three days or more, according to some customers who complained on social media such as Twitter and U-verse’s Facebook page. AT&T has said the problem affected less than 1 percent of U-verse subscribers and was concentrated in its Southeast and Southwest service areas.

“U-verse service has been fixed for all impacted customers. We’ll be crediting those affected & we’re incredibly sorry for the inconvenience,” the carrier said via Twitter around 11 a.m. Pacific time on Thursday. It had said service would be restored on Thursday morning.

In response to a question on Twitter, AT&T said all affected customers will receive a credit whether they reported an outage or not.

The outage was caused by a problem on AT&T’s servers that was related to a software update, according to the carrier.

“The software problem causing the issues was resolved by AT&T engineers early this morning. We are not pleased it took so long to fix the issue,” the company said in a statement on Thursday.

The episode set off a firestorm of criticism on social media as customers complained about the loss of service and, in some cases, customer service in response to the problem. With U-verse serving approximately 7.4 million subscribers as of last September, even an outage that hit less than 1 percent of those users could have affected tens of thousands of people, many of whom are no longer content to report failures privately to service providers.

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